Centralize proxy HTTP client creation in aiutil and remove redundant backend tests

[Copilot]

makeHTTPClient(proxyURL) had been duplicated across AI backends with equivalent behavior. This change consolidates the logic into a single helper in aiutil and updates backends to consume it, then removes backend-local tests that only re-verified that shared utility behavior.

• Shared client construction

  • Added aiutil.MakeHTTPClient(proxyURL string) (*http.Client, error) in pkg/aiusechat/aiutil/aiutil.go.
  • Standardizes proxy parsing and http.Transport.Proxy setup in one place.
  • Keeps streaming-safe client semantics (Timeout: 0) and existing invalid proxy URL error behavior.

• Backend refactor

  • Removed duplicated client/proxy setup blocks from:
    • pkg/aiusechat/openaichat/openaichat-backend.go
    • pkg/aiusechat/gemini/gemini-backend.go
    • pkg/aiusechat/openai/openai-backend.go
    • pkg/aiusechat/anthropic/anthropic-backend.go
  • Replaced with direct calls to the shared helper.

• Test cleanup

  • Deleted backend tests that only covered basic proxy client creation and no backend-specific behavior:
    • pkg/aiusechat/openaichat/openaichat-backend_test.go
    • pkg/aiusechat/gemini/gemini-backend_test.go

httpClient, err := aiutil.MakeHTTPClient(chatOpts.Config.ProxyURL)
if err != nil {
    return nil, nil, nil, err
}
resp, err := httpClient.Do(req)

---

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[kilo-code-bot]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

Files Reviewed (9 files)

• pkg/aiusechat/aiutil/aiutil.go - Added shared MakeHTTPClient utility function
• pkg/aiusechat/anthropic/anthropic-backend.go - Refactored to use shared utility
• pkg/aiusechat/gemini/gemini-backend.go - Refactored to use shared utility
• pkg/aiusechat/openai/openai-backend.go - Refactored to use shared utility
• pkg/aiusechat/openaichat/openaichat-backend.go - Refactored to use shared utility
• pkg/aiusechat/uctypes/uctypes.go - Removed duplicate AIModeConfig type
• pkg/aiusechat/usechat.go - Added ProxyURL to AIOptsType initialization
• pkg/wconfig/settingsconfig.go - Added ProxyURL field to AIModeConfigType
• pkg/aiusechat/usechat_mode_test.go - Added test for ProxyURL preservation

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Review Notes

This PR successfully adds proxy URL support to all AI backends through a clean refactoring:

✅ Code Quality: Excellent code deduplication by extracting duplicate proxy setup logic into a shared utility function

✅ Error Handling: All error cases properly handled with descriptive error messages

✅ Test Coverage: Added appropriate test to verify ProxyURL is preserved through provider defaults

✅ Consistency: All AI backends (Anthropic, OpenAI, Gemini, OpenAIChat) now use the same proxy implementation

✅ Backward Compatible: Empty ProxyURL means no proxy, maintaining existing behavior

✅ Schema Updated: JSON schema correctly updated with the new field

The implementation follows the project's coding conventions and best practices.